Tribeca Enterprises has sold a 50 percent stake to Madison Square Garden in a deal that values the indie-flick company at $45 million.

Tribeca, co-founded by Robert DeNiro to help downtown recovery efforts after the Sept. 11 attacks, produces its annual namesake festival in New York in addition to running a local theater and a digital studio.

The deal, which will allow MSG to gain majority ownership over time, promises to beef up Tribeca’s profile with its marketing heft as it strives for an international footprint.

Likewise, the agreement will give an entry into the film business for MSG owner Jimmy Dolan, whose properties also include the New York Knicks, the New York Rangers, Radio City Music Hall and the Beacon Theater.

Kicking off the new combination, Tribeca will launch its annual film festival next month by selling tickets to an event at the Beacon Theatre.

The deal comes on the heels of a setback for Dolan. On Friday, MSG Productions said “Heart and Lights,” a new dance-oriented show at Radio City featuring the Rockettes, was canceled less than a week before its scheduled opening and delayed until at least 2015.

Separately, Dolan, who is also CEO of Cablevision, is looking to sell MSG’s music cable channel Fuse. Interested buyers include Sean “Diddy” Combs and NuvoTV, which is backed by Jennifer Lopez, insiders said.

Artist Series emerged as another suitor Saturday with an offer of $350 million, though it said it hasn’t lined up financing yet. That’s above previous bids of about $200 million.